Optical discs are well known as information recording mediums exchangeable among a plurality of apparatuses. Optical discs are roughly categorized into three types, i.e., read-only type, write once type, and rewritable type. A write once optical disc allows data to be written only once at the same position thereof. For example, CD-R and DVD-R are write once optical discs. A rewritable optical disc allows data to be written many times at the same position thereof. For example, CD-RW and DVD-RAM are rewritable optical discs.
An optical disc is an exchangeable information recording medium, and therefore the surface thereof may be flawed or may have dust attached thereto, for example, at the time of, or during, exchange. A flaw or dust is treated as a defect existent on the recording layer. In order to guarantee the reliability of the information to be recorded or reproduced, defect management needs to be done.
As a conventional defect management method, Patent Document 1, for example, discloses the following. Two defect management information areas (defect management areas (DMAs)) are allocated at prescribed positions in an inner zone and prescribed positions in an outer zone (four areas in total) of a rewritable optical disc (for example, an DVD-RAM), and a DDS (Data Definition Structure) which defines the disc structure and a defect management list (Defect List) are recorded in these management information areas.
Conventionally, in order to enable information to be read from a write once optical disc by an optical disc reproduction apparatus (for example, a DVD player) usable for reading data only from a read-only optical disc, the write once optical disc needs to be subjected to finalize processing. The write once optical disc, when being finalized, obtains a data structure compatible with the data structure of the read-only optical disc. Such a write once optical disc is changed from a rewritable state into an un-rewritable state.
Recently, format establishment and development of Blu-ray discs, which are large capacity optical discs preferable for storing high quality video data such as high definition video data or the like, have been progressively conducted (for example, Non-patent Document 1). Strict defect management is applied to write once Blu-ray discs because these discs provide high quality and large capacity.
Considerations have been given to compatibility of write once Blu-ray discs with rewritable Blu-ray discs. The Blu-ray disc format is defined such that a write once Blu-ray disc, when being changed from a rewritable state into an un-rewritable state by finalization, obtains the same data arrangement and the same data structure of management information as those of a rewritable Blu-ray disc. Namely, a write once Blu-ray disc is finalized by recording of management information in a DMA area so as to have a data structure compatible with that of a rewritable Blu-ray disc and so as to be fixed to an un-rewritable state from a rewritable state.
FIG. 19 shows a structure of a conventional optical disc.
An optical disc 21 has a spiral track groove 22 formed on a discus-shaped substrate. The track groove 22 has a plurality of blocks 23 formed therein. A block 23 is an error correction unit and is also a minimum unit for information recording and information reproduction.
The optical disc 21 includes a lead-in area 24, a user data area 25, and a lead-out area 26. User data is written to, or read from, the user data area 25.
The lead-in area 24 and the lead-out area 26 are redundant areas with a track groove, which are provided such that even if an optical head (not shown) accessing an end of the user data area 25 overruns, tracking is still possible. The lead-in area 24 and the lead-out area 26 are not permitted to be accessed by a user (for recording or reproduction at a prescribed address), but management data or the like may be written in one of, or both of, the lead-in area 24 and the lead-out area 26.
In the lead-in area 24, management information areas 28a and 28b, an indicator area 27, and a temporary management information area 29 are provided. In the management information areas 28a and 28b, management information for managing a recording state of the optical disc 21 is recorded. In the indicator area 27, indicator information which indicates whether or not the management information areas 28 and the temporary management information area 29 are in a recorded state.
In the lead-out area 26, a management information area 28c is provided. In the management information area 28c, management information for managing a recording state of the optical disc 21 is recorded.
FIG. 20 shows a data structure of a conventional write once disc. At the left end of FIG. 20, the indicator area 27, the management information areas 28a through 28c, and the temporary management information area 29 described above with reference to FIG. 19 are shown.
The indicator area 27 includes an access indicator 27a. The access indicator 27a includes DMA recorded-state information 35 and TDMA recorded-state information 36. The DMA recorded-state information 35 is a copy 39 of a DDS 37 to be recorded in a DMA1 area 31.
In the management information areas 28a through 28c, the DMA1 area 31, a DMA2 area 32, a DMA3 area 33 and a DMA4 area 34 in which management information is to be recorded during finalize processing are located discretely. In each area, disc management information (DDS 37 and DFL 38) is recorded.
In one DMA area, the DFL 38 is multiple-recorded with the same content. The DDS 37 has DFL recording position information 40. The DFL recording position information 40 indicates a recording position at which the DFL 48 can be normally reproduced.
The temporary management information area 29 has a TDMA area 30 for temporarily recording management information until finalization. In the TDMA area 30, a newer and newer DDS 37 and a newer and newer DFL 38 are recorded in an additive manner.
FIG. 7 is a flowchart showing an example of a procedure for acquiring management information. A conventional optical disc apparatus, when an optical disc is mounted thereon, acquires the access indicator 27a (step 401) and determines a target area from which the management information is to be acquired (step 402).
When the DMA recorded-state information 35 is not recorded and the TDMA recorded-state information 36 is recorded, the optical disc apparatus performs acquisition processing of the management information from the TDMA area 36 (step 403). When the management information can be acquired from the TDMA 30, the optical disc apparatus determines that the mounted optical disc is a finalized disc (step 405). When the management information cannot be acquired, the optical disc apparatus determines that the mounted optical disc is an abnormal disc (step 406).
By contrast, when the DMA recorded-state information 35 is recorded, the optical disc apparatus performs acquisition processing of the management information from the DMA area (DMA1 area 31 through DMA4 area 34) (step 407). When the management information can be acquired, the optical disc apparatus determines that the mounted optical disc is a finalized disc (step 409). When the management information cannot be acquired, the optical disc apparatus determines that the mounted optical disc is an abnormal disc (step 406).
Now, finalize processing will be described. The following procedure for finalize processing will not be described as a procedure actually executed by existing optical disc apparatuses, but as an example of conceivable processing.
FIG. 8 and FIG. 10 are flowcharts each showing an example of a procedure of the finalize processing.
The conventional optical disc apparatus executes the finalize processing upon receiving a finalization instruction from an upper-level control apparatus. The finalize processing for an optical disc is implemented by step (A) of recording management information in the DMA1 area 31 through the DMA4 area 34 and step (B) of recording the access indicator 27a (DMA recorded-state information 35). For example, Patent Document 2 discloses such processing.
FIG. 8 is a flowchart showing a procedure of the finalize processing by which step (A) of recording management information in the DMA1 area 31 through the DMA4 area 34 is first executed, and then step (B) of recording the access indicator 27a is executed.
FIG. 9 shows a recording state of the optical disc finalized by the recording method shown in FIG. 8. (a) through (f) of FIG. 9, which respectively correspond to (a) through (f) of FIG. 8, show the state of the optical disc at the respective time.
FIG. 10 is a flowchart showing a procedure of the finalize processing by which step (B) of recording the access indicator 27a is first executed, and then step (A) of recording management information in the DMA1 area 31 through the DMA4 area 34 is executed.
Patent Document 1: Japanese Laid-Open Patent Publication No. 5-2837
Patent Document 2: Japanese Laid-Open Patent Publication No. 2005-276433
Non-patent Document 1: White Paper BD-R Physical Specifications, February 2006 (URL: http://www.blu-raydisc.com/assets/downloadablefile/BD-R_Physical—3rd_edition—0602f1-13322.pdf)